Process for Preparing Substituted Biphenyls

ABSTRACT

A process for preparing substituted biphenyls of the formula I 
     
       
         
         
             
             
         
       
     
     in which the substituents are defined as follows:
         X is fluorine or chlorine;   R 1  is nitro, amino or NHR 3 ;   R 2  is cyano, nitro, halogen, C 1 -C 6 -alkyl, C 1 -C 6 -alkenyl, C 1 -C 6 -alkynyl, C 1 -C 6 -alkoxy, C 1 -C 6 -haloalkyl, C 1 -C 6 -alkylcarbonyl or phenyl;   R 3  is C 1 -C 4 -alkyl, C 1 -C 4 -alkenyl or C 1 -C 4 -alkynyl;   n is 1, 2 or 3, where in case that n is 2 or 3, the R 2  radicals may also be different,
 
which comprises reacting the compound of the formula II
       

     
       
         
         
             
             
         
       
     
     in which Hal is halogen and X and R 1  are as defined above, in the presence of a base and of a palladium catalyst selected from the group of:
         a) palladium-triarylphosphine or -trialkylphosphine complex with palladium in the zero oxidation state,   b) salt of palladium in the presence of triarylphospine or trialkylphosphine as a complex ligand or   c) metallic palladium, optionally applied to support,
 
in the presence of triarylphosphine or trialkylphosphine, in a solvent, with a diphenylborinic acid (III)
       

     
       
         
         
             
             
         
       
     
     in which R 2  and n are as defined above, where the triarylphosphines or trialkylphosphines used may be substituted.

The present invention relates to a process for preparing substitutedbiphenyls of the formula I

in which the substituents are defined as follows:

-   -   X is fluorine or chlorine;    -   R¹ is nitro, amino or NHR³;    -   R² is cyano, nitro, halogen, C₁-C₆-alkyl, C₁-C₆-alkenyl,        C₁-C₆-alkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkyl,        (C₁-C₆-alkyl)carbonyl or phenyl;    -   R³ is C₁-C₄-alkyl, C₁-C₄-alkenyl or C₁-C₄-alkynyl;    -   n is 1, 2 or 3, where in case that n is 2 or 3, the R² radicals        may also be different,        which comprises reacting a compound of formula 11

in which Hal is halogen and X and R¹ are as defined above, in thepresence of a base and of a palladium catalyst selected from the groupof:

-   -   a) palladium-triarylphosphine or -trialkylphosphine complex with        palladium in the zero oxidation state,    -   b) salt of palladium in the presence of triarylphospine or        trialkylphosphine as a complex ligand or    -   c) metallic palladium, optionally applied to support,        in the presence of triarylphosphine or trialkylphosphine, in a        solvent, with a diphenylborinic acid (III)

in which R¹ and n are as defined above, where the triarylphosphines ortrialkylphosphines used may be substituted.

Tetrahedron Lett. 32, page 2277 (1991) states that the coupling reactionbetween phenylboronic acid and chlorobenzene with use of the[1,4-bis(diphenylphosphine)-butane]palladium(II) dichloride catalystproceeds with a yield of only 28%.

EP-A 0 888 261 discloses a process for preparing nitrobiphenyls byreacting chloronitrobenzenes with a phenylboronic acid in the presenceof a palladium catalyst and of a base. In this process, a very highcatalyst concentration is necessary.

It was therefore an object of the present invention to provide aneconomically viable process which can be implemented on the industrialscale for regioselectively preparing substituted biphenyls, which workswith a reduced palladium catalyst concentration.

Accordingly, the process defined at the outset has been found.

The diphenylborinic acid (III) is obtained by reaction of optionallysubstituted phenylmagnesium chloride V with trialkyl borate, preferablytrimethyl borate, in tetrahydrofuran as a solvent according to scheme 1which follows.

R⁴ is C₁-C₄-alkyl, preferably methyl.

Essential for a high yield of diphenylborinic acid (III) is the use ofonly 0.7 eq. of trialkyl borate based on the substituted chlorobenzene(IV) used. Use of 1.1 eq. of trialkyl borate gives rise to phenylboronicacid as described in EP-A 0 888 261.

This reduction in the trialkyl borate use has several surprisingadvantages in relation to the preparation of nitrobiphenyls (I). Thespace-time yield is increased. The feedstock costs are lowered as aresult of reduction in the amount of expensive trimethyl borate. Unlikethe phenylboronic acids used in EP-A 0 888 261, the diphenylborinicacids (III) are soluble in tetrahydrofuran, which leads to animprovement in heat removal during the reaction, which is accompanied bylower consumption of the cooling capacity. This leads in turn to higherprocess safety.

The reaction temperature in this process stage is from 10 to 30° C.,preferably from 15 to 25° C.

The substituted biphenyls prepared by the present process have thefollowing preferred substituents, in each case both individually and incombination:

-   -   R¹ nitro, amino, methylamino, propylamino, butylamino,        allylamino or propargylamino,    -   more preferably nitro, amino or methylamino,    -   most preferably nitro or amino;    -   R² cyano, nitro, fluorine, chlorine, bromine, methyl, ethyl,        propyl, butyl, allyl,    -   propargyl, methoxy, ethoxy, trifluoromethyl or phenyl,    -   more preferably fluorine, chlorine, methyl or methoxy,    -   most preferably fluorine or chlorine;    -   R³ methyl, ethyl, propyl, butyl, allyl or propargyl,    -   more preferably methyl, ethyl or allyl,    -   most preferably methyl;    -   n 1 or 2, preferably 2.

The subsequent homogeneously catalyzed Suzuki biaryl cross-coupling iscarried out according to scheme 2.

Preference is given to starting from diphenylborinic acids of theformula (III) in which R² and n are as defined above.

Further preferred starting materials are diphenylborinic acids (III) inwhich n is 1 or 2, in particular 2. Particularly preferred arediphenylborinic acids (III) which are substituted in the 3- and4-position.

Very particular preference is given to di(2,3-difluorophenyl)borinicacid, di(3,4-difluorophenyl)borinic acid, di(2,3-dichlorophenyl)borinicacid and in particular di(3,4-dichlorophenyl)borinic acid as thestarting compound (III).

Preference is given to starting from the following compounds (II):

2-bromo-4-fluoroaniline, 2-chloro-4-fluoroaniline and in particular2-chloro-4-fluoro-1-nitrobenzene or 2-bromo-4-fluoro-1-nitrobenzene.

The compound (II) is used, based on the diphenylborinic acids (III)(diphenylborinic acid equivalents), normally in an equimolar amount,preferably with an up to 20 percent excess, in particular with an up to50 percent excess.

The bases used may be organic bases, for example tertiary amines.Preference is given to using, for example, triethylamine ordimethylcyclohexylamine.

The bases used are preferably alkali metal hydroxides, alkaline earthmetal hydroxides, alkali metal carbonates, alkaline earth metalcarbonates, alkali metal hydrogen-carbonates, alkali metal acetates,alkaline earth metal acetates, alkali metal alkoxides and alkaline earthmetal alkoxides, in a mixture and in particular individually.

Particularly preferred bases are alkali metal hydroxides, alkaline earthmetal hydroxides, alkali metal carbonates, alkaline earth metalcarbonates and alkali metal hydrogencarbonates.

Especially preferred bases are alkali metal hydroxides, e.g. sodiumhydroxide and potassium hydroxide, and also alkali metal carbonates andalkali metal hydrogencarbonates, e.g. lithium carbonate, sodiumcarbonate and potassium carbonate.

The base is used in the process according to the invention preferablywith a fraction of from 100 to 500 mol %, more preferably from 150 to400 mol %, based on the amount of diphenylborinic acid (III).

Suitable palladium catalysts are palladium-ligand complexes withpalladium in the zero oxidation state, salts of palladium in thepresence of complex ligands, or metallic palladium optionally applied tosupport, preferably in the presence of complex ligands.

Suitable complex ligands are uncharged ligands such as triarylphosphinesand trialkylphosphines, which may optionally be substituted in the arylrings, such as triphenylphosphine (TPP),di-1-adamantyl-n-butylphosphine, tri-tert-butylphosphine (TtBP) or2-(dicyclohexylphosphino)biphenyl.

Furthermore, the literature has also described further particularlyreactive complex ligands from other structural classes, including1,3-bis(2,6-diisopropylphenyl)-4,5-H2-imidazolium chloride (cf., forexample, G. A. Grasa et al. Organometallics 2002, 21, 2866) andtris(2,4-di-tert-butylphenyl) phosphite (cf. A. Zapf et al., Chem. Eur.J. 2000, 6, 1830).

The reactivity of the complex ligands can be enhanced by adding aquaternary ammonium salt such as tetra-n-butylammonium bromide (TBAB)(cf., for example, D. Zim et al., Tetrahedron Lett. 2000, 41, 8199).

If required, the water solubility of the palladium complexes can beimproved by various substituents such as sulfonic acid or sulfonate saltgroups, carboxylic acid or carboxylate salt groups, phosphonic acid,phosphonium or phosphonate salt groups, peralkylammonium, hydroxyl andpolyether groups.

Among the palladium-ligand complexes with palladium in the 0 oxidationstate, preference is given to usingtetrakis(triphenylphosphine)palladium and additionallytetrakis[tri(o-tolyl)phosphine]palladium.

In the salts of palladium which are used in the presence of complexligands, the palladium is normally present in the two positive oxidationstate. Preference is given to using palladium chloride, palladiumacetate or bisacetonitrilepalladium chloride. Particular preference isgiven to using palladium chloride.

In general, from 6 to 60, preferably from 15 to 25, equivalents of theaforementioned complex ligands, in particular triphenylphosphine andtri-tert-butylphosphine, are combined with one equivalent of thepalladium salt.

EP-A 0 888 261 describes the use of from 2 to 6 equivalents oftriphenylphosphine per equivalent of the palladium catalyst. The use ofhigh ligand excesses is generally viewed in the literature asdisadvantageous, since this is expected to result in inactivation of thecatalytically active complex (cf., for example, J. Hassan et al., Chem.Rev. 2002,102,1359).

It was thus surprising that this high triphenylphosphine use incombination with the low catalyst use led to an increase in the overallyield of the process of the present invention and accordingly to animprovement in the economic viability.

Metallic palladium is used preferably in pulverized form or on a supportmaterial, for example in the form of palladium on activated carbon,palladium on alumina, palladium on barium carbonate, palladium on bariumsulfate, palladium on calcium carbonate, palladium aluminosilicates suchas montmorillonite, palladium on SiO₂ and palladium on calciumcarbonate, in each case with a palladium content of from 0.5 to 12% byweight. In addition to palladium and the support material, thesecatalyst may comprise further dopants, for example lead.

When metallic palladium optionally applied to support is used,particular preference is given to also using the aforementioned complexligands, in particular to the use of palladium on activated carbon inthe presence of triphenylphosphine as a complex ligand, where the phenylgroups in the triphenylphosphine are preferably substituted by a totalof from one to three sulfonate groups.

In the process according to the invention, the palladium catalyst isused with a low fraction of from 0.001 to 1.0 mol %, preferably from0.005 to 0.5 mol % or from 0.01 to 0.5 mol % and in particular from0.005 to 0.05 mol %, based on the amount of compound (II).

The low use of a palladium salt in combination with a high use of acomplex ligand constitutes a significant cost advantage of this processover the prior art processes.

The process according to the invention may be carried out in a biphasicsystem composed of aqueous phase and solid phase, i.e. the catalyst. Inthat case, the aqueous phase may also comprise a water-soluble organicsolvent in addition to water.

Organic solvents suitable for the process according to the invention areethers such as dimethoxyethane, diethylene glycol dimethyl ether,tetrahydrofuran, dioxane and tert.-butyl methyl ether, hydrocarbons suchas n-hexane, n-heptane, cyclohexane, benzene, toluene and xylene,alcohols such as methanol, ethanol, 1-propanol, 2-propanol, ethyleneglycol, 1-butanol, 2-butanol and tert.-butanol, ketones such as acetone,ethyl methyl ketone and isobutyl methyl ketone, amides such asdimethylformamide, dimethylacetamide and N-methylpyrrolidone, in eachcase individually or in a mixture.

Preferred solvents are ethers such as dimethoxyethane, tetrahydrofuranand dioxane, hydrocarbons such as cyclohexane, toluene and xylene,alcohols such as ethanol, 1-propanol, 2-propanol, 1-butanol andtert.-butanol, in each case individually or in a mixture.

In a particularly preferred variant of the process according to theinvention, water, one or more water-insoluble and one or morewater-soluble solvents are used, for example mixtures of water anddioxane, or water and tetrahydrofuran, or water, dioxane and ethanol, orwater, tetrahydrofuran and methanol, or water, toluene andtetrahydrofuran, preferably water and tetrahydrofuran, or water,tetrahydrofuran and methanol.

The total amount of solvent is normally from 3000 to 500 g andpreferably from 2000 to 700 g, per mole of the compound (II).

Appropriately, the process is carried out by adding the compound (II),the diphenyl-borinic acids (III), the base and the catalytic amount ofthe palladium catalyst to a mixture of water and one or more inertorganic solvents, and stirring at a temperature of from 50° C. to 120°C., preferably from 70° C. to 110° C., more preferably from 90° C. to100° C., for a period of from 1 to 50 hours, preferably from 2 to 24hours.

Depending on the solvent and temperature used, a pressure of from 1 barto 6 bar, preferably from 1 bar to 4 bar, is established.

Preference is given to carrying out the reaction in water andtetrahydrofuran.

The reaction may be carried out in customary apparatus suitable for suchprocesses.

On completion of reaction, palladium catalyst obtained as a solid isremoved, for example by filtration, and the crude product is freed fromthe solvent or the solvents.

In the case of products which are not fully water-soluble, water-solublepalladium catalysts or complex ligands are removed fully from the crudeproduct in the separation of the water phase.

Subsequently, further purification may be effected by methods which areknown to those skilled in the art and are appropriate to the particularproduct, for example by recrystallization, distillation, sublimation,zone melting, melt crystallization or chromatography.

By the process according to the invention, it is possible to prepare,for example:

-   -   3′,4′-dichloro-5-fluoro-biphenyl-2-ylamine,    -   2′,3′-dichloro-5-fluoro-biphenyl-2-ylamine,    -   3′,4′-dichloro-3-fluoro-biphenyl-2-ylamine,    -   2′,3′-dichloro-3-fluoro-biphenyl-2-ylamine,    -   3′,4′-dichloro4-fluoro-biphenyl-2-ylamine,    -   2′,3′-dichloro4-fluoro-biphenyl-2-ylamine,    -   3′,4′-dichloro-6-fluoro-biphenyl-2-ylamine,    -   2′,3′-dichloro-6-fluoro-biphenyl-2-ylamine,    -   3′,4′-difluoro-5-fluoro-biphenyl-2-ylamine,    -   2′,3′-difluoro-5-fluoro-biphenyl-2-ylamine,    -   3′,4′-difluoro-3-fluoro-biphenyl-2-ylamine,    -   2′,3′-difluoro-3-fluoro-biphenyl-2-ylamine,    -   3′,4′-difluoro-4-fluoro-biphenyl-2-ylamine,    -   2′,3′-difluoro4-fluoro-biphenyl-2-ylamine,    -   3′,4′-difluoro-6-fluoro-biphenyl-2-ylamine,    -   2′,3′-dichloro-6-fluoro-biphenyl-2-ylamine,    -   3′,4′-dichloro-5-chloro-biphenyl-2-ylamine,    -   2′,3′-dichloro-5- chloro-biphenyl-2-ylamine,    -   3′,4′-dichloro-3-chloro-biphenyl-2-ylamine,    -   2′,3′-dichloro-3-chloro-biphenyl-2-ylamine,    -   3′,4′-dichloro-4-chloro-biphenyl-2-ylamine,    -   2′,3′-dichloro-4-chloro-biphenyl-2-ylamine,    -   3′,4′-dichloro-6-chloro-biphenyl-2-ylamine,    -   2′,3′-dichloro-6-chloro-biphenyl-2-ylamine,    -   3′,4′-difluoro-5-chloro-biphenyl-2-ylamine,    -   2′,3′-difluoro-5-chloro-biphenyl-2-ylamine,    -   3′,4′-difluoro-3-chloro-biphenyl-2-ylamine,    -   2′,3′-difluoro-3-chloro-biphenyl-2-ylamine,    -   3′,4′-difluoro-4-chloro-biphenyl-2-ylamine,    -   2′,3′-difluoro-4-chloro-biphenyl-2-ylamine,    -   3′,4′-difluoro-6-chloro-biphenyl-2-ylamine,    -   2′,3′-dichloro-6-chloro-biphenyl-2-ylamine,    -   3′,4′-dichloro-5-fluoro- 2-nitrobiphenyl,    -   2′,3′-dichloro-5-fluoro-2-nitrobiphenyl,    -   3′,4′-dichloro-3-fluoro-2-nitrobiphenyl,    -   2′,3′-dichloro-3-fluoro-2-nitrobiphenyl,    -   3′,4′-dichloro-4-fluoro-2-nitrobiphenyl,    -   2′,3′-dichloro-4-fluoro-2-nitrobiphenyl,    -   3′,4′-dichloro-6-fluoro-2-nitrobiphenyl,    -   2′,3′-dichloro-6-fluoro-2-nitrobiphenyl,    -   3′,4′-difluoro-5-fluoro-2-nitrobiphenyl,    -   2′,3′-difluoro-5-fluoro-2-nitrobiphenyl,    -   3′,4′-difluoro-3-fluoro-2-nitrobiphenyl,    -   2′,3′-difluoro-3-fluoro-2-nitrobiphenyl,    -   3′,4′-difluoro-4-fluoro-2-nitrobiphenyl,    -   2′,3′-difluoro-4-fluoro-2-nitrobiphenyl,    -   3′,4′-difluoro-6-fluoro-2-nitrobiphenyl,    -   2′,3′-dichloro-6-fluoro-2-nitrobiphenyl,    -   3′,4′-dichloro-5-chloro-2-nitrobiphenyl,    -   2′,3′-dichloro-5- chloro-2-nitrobiphenyl,    -   3′,4′-dichloro-3-chloro-2-nitrobiphenyl,    -   2′,3′-dichloro-3-chloro-2-nitrobiphenyl,    -   3′,4′-dichloro-4-chloro-2-nitrobiphenyl,    -   2′,3′-dichloro-4-chloro-2-nitrobiphenyl,    -   3′,4′-dichloro-6-chloro-2-nitrobiphenyl,    -   2′,3′-dichloro-6-chloro-2-nitrobiphenyl,    -   3′,4′-difluoro-5-chloro-2-nitrobiphenyl,    -   2′,3′-difluoro-5-chloro-2-nitrobiphenyl,    -   3′,4′-difluoro-3-chloro-2-nitrobiphenyl,    -   2′,3′-difluoro-3-chloro-2-nitrobiphenyl,    -   3′,4′-difluoro4-chloro-2-nitrobiphenyl,    -   2′,3′-difluoro-4-chloro-2-nitrobiphenyl,    -   3′,4′-difluoro-6-chloro-2-nitrobiphenyl,    -   2′,3′-dichloro-6-chloro-2-nitrobiphenyl.

The process according to the invention affords the compounds I in veryhigh up to quantitative yields at very good purity.

The substituted biphenyls obtainable by the process according to theinvention are suitable as precursors for fungicidal crop protectionactive ingredients (cf. WO 03/070705).

Synthesis of 3′,4′-dichloro-5-fluoro-2-nitro-biphenyl

EXAMPLE 1 Di-(3,4-dichlorophenyl)borinic acid

A solution of 12.81 g of trimethyl borate (123 mM) and 30 mL oftetrahydrofuran is heated to reflux. To this are metered 245 g of a 18%by weight solution of 3,4-dichlorophenylmagnesium bromide (177 mM) intetrahydrofuran within 1 hours. After full addition, the reactionsolution is stirred at reflux for another hour.

The reaction solution is subsequently treated with 110 mL of 10% aqueoushydrochloric acid and stirred at 40° C. for 30 minutes. After phaseseparation, a solution of di(3,4-dichlorophenyl)borinic acid intetrahydrofuran is obtained. 32.1 g of di(4-chlorophenyl)borinic acid isisolated by crystallization from 200 mL of hexane (yield 57%). MS:m/z=320 [m+H]⁺, ¹H-NMR (DMSO, 500 MHz): δ [ppm]=7.51 (s, 1H), 7.38 (d,1H, 7 Hz), 7.27 (d, 1H, 7 Hz).

EXAMPLE 2 Reaction of di(3,4-dichlorophenyl)borinic acid and2-bromo4-fluoro-aniline

A reaction flask is initially charged with 0.55 g of sodium hydroxide(13.7 mM) and 50 mL of water at 15-20° C.

To this are metered 2.5 g of di(3,4-dichlorophenyl)borinic acid (7.8 mM)and 0.199 g of triphenylphosphine (0.76 mM) in 50 mL of dioxane. Afterfull addition, the reaction solution is stirred at 18-22° C. for 40minutes. After deoxygenation, 27 mg of palladium(II) chloride (0.15 mM)and 1,4 g of 2-bromo4-fluoro-aniline (7.4 mM) are added to the reactionsolution. The reaction solution is heated to 85° C. for 6 hours. Thereaction mixture is cooled down, acidified with 2 M hydrochloric acidand the dioxane evaporated. The residue is extracted withdichloromethane and after evaporation of solvent the3′,4′-dichloro-5-fluoro-biphenyl-2-ylamine is isolated by columnchromatography (0.63 g, yield 33%).

HPLC-MS: m/z=256.0 [m+H]⁺

EXAMPLE 3 Reaction of di(3,4-dichlorophenyl)borinic acid and2-chloro-4-fluoro-1-nitro-benzene

A reaction flask is initially charged with 0.55 g of sodium hydroxide(13.7 mM) and 50 mL of water at 15-20° C.

To this are metered 2.5 g of di(3,4-dichlorophenyl)borinic acid (7.8 mM)and 0.199 g of triphenylphosphine (0.76 mM) in 50 mL of dioxane. Afterfull addition, the reaction solution is stirred at 18-22° C. for 40minutes. After deoxygenation, 27 mg of palladium(II) chloride (0.15 mM)and 1.3 g of 2-chloro-4-fluoro-1-nitro-benzene (7.4 mM) are added to thereaction solution. The reaction solution is heated to 85° C. for 6hours.

The reaction mixture is cooled down, acidified with 2 M hydrochloricacid and the dioxane evaporated. The residue is extracted withdichloromethane and after evaporation of solvent the3′,4′-dichloro-5-fluoro-2-nitro-biphenyl is isolated by columnchromatography (0.76 g, yield 36%).

GC-MS: m/z=285.9 [m−H]⁻

1-15. (canceled)
 16. A process for preparing substituted biphenyls ofthe formula I

in which the substituents are defined as follows: X is fluorine orchlorine; R¹ is nitro, amino or NHR³; r² is cyano, nitro, halogen,C₁-C₆-alkyl, C₁-C₆-alkenyl, C₁-C₆-alkynyl, C₁-C₆-alkoxy,C₁-C₆-haloalkyl, (C₁-C₆-alkyl)carbonyl or phenyl; r³ is C₁-C₄-alkyl,C₁-C₄-alkenyl or C₁-C₄-alkynyl; n is 1, 2 or 3, where in case that n is2 or 3, the R² radicals may also be different, which comprises reactingthe compound of the formula II

in which Hal is halogen and X and R¹ are as defined above, in thepresence of a base and of a palladium catalyst selected from the groupof: a) palladium-triarylphosphine or -trialkylphosphine complex withpalladium in the zero oxidation state, b) salt of palladium in thepresence of triarylphospine or trialkylphosphine as a complex ligand orc) metallic palladium, optionally applied to support, in the presence oftriarylphosphine or trialkylphosphine, in a solvent, with adiphenylborinic acid III

in which R² and n are as defined above, where the triarylphosphines ortrialkylphosphines used may be substituted.
 17. The process according toclaim 16, wherein the compound II used is 2-nitro-3-fluoro-chlorobenzeneor 2-amino-3-fluoro-bromobenzene.
 18. The process according to claim 16,wherein the starting compound III is a diphenylborinic acid which issubstituted in the 3- and 4-position.
 19. The process according to claim16, wherein a diphenylborinic acid III is used which bears fluorine orchlorine in the 3- and 4-positions.
 20. The process according to claim16, wherein the starting compound III is di(3,4-dichlorophenyl)borinicacid.
 21. The process according to claim 16, wherein the palladiumcatalyst a) according to claim 1 used istetrakis(triphenylphosphine)palladium ortetrakis(tri-tert.-butylphosphine)palladium.
 22. The process accordingto claim 16, wherein a palladium catalyst b) according to claim 1 isused.
 23. The process according to claim 16, wherein the palladiumcatalyst c) according to claim 1 used is metallic palladium on activatedcarbon in the presence of triphenylphosphine whose phenyl groups aresubstituted by a total of from 1 to 3 sulfonate groups.
 24. The processas claimed in claim 22, wherein the salt of the palladium catalyst b)used is palladium chloride, palladium acetate orbisacetonitrilepalladium chloride.
 25. The process according to claim22, wherein a palladium catalyst b) is used for which from 6 to 60equivalents of triphenylphosphine are used per equivalent of thepalladium salt.
 26. The process according to claim 16, wherein from0.001 to 1.0 mol % of the palladium catalyst is used, based on theamount of compound II.
 27. The process according to claim 16, whereinthe reaction is carried out at a temperature of from 50 to 120° C. 28.The process according to claim 16, wherein the reaction is carried outin a mixture of water and an organic solvent.
 29. The process accordingto claim 28, wherein the organic solvent used is an ether.
 30. Theprocess according to claim 16, wherein the reactions are carried out ata pressure of from 1 to 6 bar. 31.3′,4′-dichloro-5-fluoro-2-nitro-biphenyl.
 32. The process according toclaim 17, wherein the starting compound III is a diphenylborinic acidwhich is substituted in the 3- and 4-position.
 33. The process accordingto claim 17, wherein a diphenylborinic acid III is used which bearsfluorine or chlorine in the 3- and 4-positions.
 34. The processaccording to claim 17, wherein the starting compound III isdi(3,4-dichlorophenyl)borinic acid.
 35. The process according to claim17, wherein the palladium catalyst a) according to claim 1 used istetrakis(triphenylphosphine)palladium ortetrakis(tri-tert.-butylphosphine)palladium.